The present invention refers to connecting links belonging into the last mentioned group. A typical example of a known connecting link of this type is described e.g. in the German patent specification No. 1,156,282 and has a massive central portion roughly corresponding to a stud in a common link and to which central portion is at each side (in the direction of a longitudinal axis of the link) a vertex portion jointed which defines a loop for accomodating an end link of an attached chain length. The link is along complementary peripheric contact surfaces divided into two identical halves comprising each one half of the central portion (divided approximately along said longitudinal axis) and one half of the rest of the link, viz. approximately three quarts of the one vertex portion and approximately one quart of the other vertex portion. The two link halves are held together by a locking means defined by a bolt extending obliquely through the central portion and by co-operating engagement means defined by two cylindrical stumps projecting one from each said contact surface of one link half and accomodated in a cylindrical recess in the corresponding contact surface of the other link half.
In all chain links there is always a risk of deformation even in transverse direction to the longitudinal axis, and the portions of the link in which said recesses are arranged are not sufficiently secured against being bent outwardly, in particular as the presence of the recesses causes a considerable local reduction of the massive part of the cross-sectional area of the link at the respective location. The recesses define also blind bores which easily may be filled by dirt obstructing ready assembly and it is also rather expensive to produce integral cylindrical stumps projecting from a surrounding surface. The peripheric contact surfaces are composed of two sections and they extend each from an origin at the outer periphery of the link to a termination at the inner periphery of one of the loops. Both the origin and the termination lie at the same side of a transverse axis of the link, bisecting the longitudinal axis thereof, and the origin is located adjacent the vertex of the link, i.e. the place where the longitudinal axis intersects the outer periphery. This, however, is a location where the link in use is exposed for maximum shear stress.
Another connecting link of said second group is described in the German patent specification No. 1,197,291. There has each contact surface the shape of a row of saw teeth, the origin and the termination lying on different sides of the transverse axis of the link. At both origins are relatively slender wedge-shaped lugs formed which upon extreme transverse stress may bend out and thus considerably augment the transverse dimension of the link.